The special features are a tad disappointing by the sounds of things. I was really hoping for a commentary from Nolan, but knowing his distaste for that kind of thing, I'm not surprised. I'm more surprised that there's no feature about The Joker or Heath Ledger's contribution. Would've really liked a Two-Face featurette as well.
Anyways, here are der special features
Gotham Uncovered – how Christopher Nolan and his team developed the new Bat-suit and Bat-pod and composer Hans Zimmer musically characterized The Joker’s reign of chaos.
The Dark Knight IMAX® scenes: view these 6 action-packed sequences
Gotham Tonight - 6 episodes of Gotham Cable’s premier news programme
The Galleries: poster art and production stills
pitiful. The second highest grossing film of all time deserves better. I'd expect a better edition further down the road